The human spinal or vertebral column consists of a plurality of separate vertebrae joined to each other to permit forward, backward and sideways movement of the column. At the lower end of the spinal column are the lumbar vertebrae which support the small of the back. Above the lumbar vertebrae are the thoracic vertebrae, which lie behind the thoracic or chest cavity. The uppermost cervical vertebrae define the skeletal framework of the neck. The vertebrae are separated and supported against each other by cartilaginous elements or discs, and are held together by ligaments. The discs are subject to deterioration and disease, often creating significant pain.
Studies have shown that the intra-disc pressure in the lumbar spine while in a supine position is in the neighborhood of 50 Kpa, while pressures while in the sitting position average between 150 and 200 Kpa. These correspond roughly to pressures of 7.5 and 30 psi. The observation that patients with herniated lumbar disc disease are often least comfortable in the sitting position may be at least partially due to such pressure differences.
Magnetic Resonance Imaging (MRI) techniques are often used in the diagnosis of lumbar disc disease. Experience has shown, however, that it is not uncommon to find a disassociation between the severity of the patient's clinical symptoms and evidence of disease shown through MRI findings. This disassociation can be in part explained by the general inability of conventional MRI diagnosis systems to allow the patient to be imaged when placed into a variety of positions, including the sitting position, to vary the intra-discal pressures and alignment of the vertebrae. The supine position, in which all MRIs of the lumbosacral spine are performed, is associated with the lowest (50 Kpa) intradiscal pressure, and is thus not a good position to provoke disc herniation, and is thus far from the optimal position for effective disc herniation diagnosis. It has been shown, for example, that an L5-S1 protrusion was noticeably augmented when the patient was in the sitting position.
It is accordingly a purpose of the present invention to provide a method and apparatus for the positioning of a patient for MRI imaging in conjunction with conventional MRI imaging units which allows the spine to be placed in an orientation which may assist in the identification of diseased areas by increasing intradiscal pressure to approximate that generated in the sitting position.
It is a further purpose of the present invention to provide a method and apparatus to allow a patient to be oriented for MRI imaging in a manner which increases the intra-discal pressure in the lumbar spinal region during the imaging process.
It is still a further purpose of the present invention to provide a method and apparatus which may be utilized in connection with MRI imaging devices of conventional construction for enhanced spinal imaging procedures and which do not compromise or affect the accuracy or operation of the MRI imaging device.